N=int(input())
A=list(map(int,input().split()))

P=sum(A)
Q=sum([i*A[i] for i in range(N)])

M=(N-1)*N*(N+1)

b=(N-1)*(2*N-1)*P-3*(N-1)*Q
b*=2/M
d=-3*(N-1)*P+6*Q
d*=2/M

X=0
p=b
for i in range(N):
    X+=pow(A[i]-p,2)
    p+=d

print(b,d)
print(X)